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Report # 147 : Traditional Naga Type House

August 22, 2011 By

by Amir Ali Khan

The housing type is most common throughout the Northeast India which lies in the most severe seismic zone of the country (Zone V – corresponding to MSK IX). Majority of this type of houses are used for residential purposes. Typically these houses are built with light weight locally available material like bamboo, wooden planks, thatch etc. These housing types have traditional system of bamboo/wooden posts. Bamboo posts are inserted into the ground to act as compression members and are tied with horizontal bamboo/wooden girders with the help of bamboo ropes (cane) to give a proper shape and framing action. However, there is no protection of bamboo/wooden posts against decaying/termites or any other natural cause. The performance of these houses during the past earthquakes is unknown. However, during the discussions with local people about the performance of these houses in the past major earthquakes, it was noted that the majority of houses survived.

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Filed Under: Asia & Mideast, India, Timber

Report # 145 : Pillar walaghar (URM infilled RC frame buildings)

August 22, 2011 By

by Yukta Bilas Marhatta, Jitendra K Bothara, Meen Bahadur Magar, Gopal Chapagain

This building type is widely constructed in the urban and semi-urban area of Nepal. It has all the characteristics of a vernacular building only with the exception that few of the construction materials are not local. It is one of the most emerging building typologies in Nepal. This is mostly non-engineered building typology. However, in urban areas sometimes competent structural engineers are also involved in the design. This technology was picked up after its relatively better performance during 1988 Udaypur earthquake which recorded M6.4 on Richter scale, that severely hit eastern Nepal. In this type of building a lightly reinforced frame is constructed first and then infill walls are erected later between columns. Though not usual, sometimes walls are constructed first and columns and beams later. These buildings serve multifunctional purposes such as residential, commercial, official, religious, educational, etc. These buildings are highly vulnerable to earthquake because of deficient detailing, inferior construction materials and the inadequate technology employed. Despite the use of modern materials of construction there is an ever growing risk to life and property due to potential earthquake attack. This building type, if designed and constructed properly, is suitable for low rise buildings up to 3 to 4 stories high. It is necessary to disseminate simple techniques of earthquake resistant measures for these buildings to the grass-root level.

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Filed Under: Asia & Mideast, Nepal, RC Moment Frame, Reinforced Concrete

Report # 143 : Mud House of Bangladesh

August 22, 2011 By

by Amrita Das, Mohammad Shariful Islam, Dr. Md. Jahangir Alam, Nusrat Hoque

In Bangladesh, a mud house is one of the traditional housing types that are used by poor families mainly in rural areas as well as in the outskirts of small cities. This building type is typically one or two stories and preferably used for single-family housing. It is more predominant in less flood-prone areas, i.e. in the highlands or in mountainous regions. The masses of these buildings are generally high and their walls are characterized by insignificant strength, particularly against forces that act out-of-plane. This type of building is highly vulnerable to both seismic forces and high pressures due to flood flow. The main load bearing system consists of mud walls of 1.5 to 3.0 ft thickness, which carry the roof load. Clay tiles, thatch or CI sheets are used as roofing materials. The application of these materials depends on their local availability and the ability of the house owners. There is no monolithic joint between the wall and the roof. For this reason, these buildings behave poorly under any type of lateral load (e.g. earthquake, wind).

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Filed Under: Adobe / Earthen, Asia & Mideast, Bangladesh

Report # 138 : Stone masonry residential buildings

August 22, 2011 By

by Qaisar Ali, Taj Muhammad

In the Northern part of Pakistan, which mostly consists of mountainous terrain and where building stones are more abundantly available than any of the alternate building material, people commonly construct single story stone masonry buildings for residential purpose. A variety of building typologies are in use. An approximate distribution of common types of such buildings is:- Stone masonry houses without mortar with earthen roof (Fig 1a). 10% Stone masonry houses in mud mortar with earthen roofs (Fig 1c). 40% Stone masonry houses in cement mortar with earthen roof (Fig 1d). 10% Stone masonry houses in cement mortar with G.I.Sheet roof (Fig 1f). 30% Stone masonry houses with R.C roofing (Fig 1g) 10%. Construction of houses in rubble stone masonry, in dry or in mud mortar, was most common and was generally practiced in the past in these areas. It is still in practice in most construction. Presently, among all, about 50% of the buildings are of this type. In new construction mud mortar is steadily being replaced with cement mortar. Wall thickness in all cases usually varies from 1 to 1 ½ ft. Roofs are usually earthen and generally consist of thatch covered with mud/earth and supported on wooden beams (or logs) and rafters. Some time wooden columns are also provided beneath the beams along the walls or in between the walls to support the roofing. Wooden rafters, planks and G.I. sheets are also used in modern construction for roofing. Any particular or regular layout is not used for construction of these residential buildings. It varies depending on the available space. Size of the building also varies from a single room to more than one room as per requirement of the family (Figs 3a–3c). These structures are considered, from experience, to be strong enough to withstand the applied gravity loads, but their seismic performance has not properly been investigated and is believed to be vulnerable to earthquake of even moderate shaking, particularly when confining elements such as wooden columns are not used. In a typical type of construction, historically known to be well resistant to seismic effects, horizontal and vertical wooden members are provided in the walls. These horizontal and vertical members are inter-connected at corners and other locations through wooden nails. The remaining space of the wall is then built in stone masonry of any type. This type of construction was commonly practiced in remote North parts of this region in the past and is still in practice for improved seismic performance in some of the buildings (figs 5a–5e).

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Filed Under: Asia & Mideast, Masonry, Pakistan, Stone Masonry

Report # 116 : Timber Frame Brick House with Attic

August 22, 2011 By

by Amit Kumar, Jeewan Pundit

This type of house is used for residential purposes. The building type under study has been picked the from central part of India (Madhya Pradesh), but it is found throughout India with small or large variations. Timber is primarily used for the frame structural elements but due to an acute shortage of timber, this construction type is not practiced anymore. Various components of the building change from place to place depending on climate, socio-economic conditions, availability of material, etc. Timber frames, placed in longitudinal and traverse directions, are filled with brick masonry walls. The floor structure is made of timber planks. Most of the buildings are found to be rectangular in shape with few openings. The roofing material is usually light when it is made from galvanized iron sheets. Seismic performance of a perfectly framed building is very satisfactory. Existing old structures, however, require maintenance and strengthening (Figure-1a,1b). It has been observed that nominal cost will be incurred for introducing earthquake resistant features.

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Filed Under: Asia & Mideast, India, Masonry, Unreinforced Masonry

Report # 112 : Unreinforced brick masonry residential building

August 22, 2011 By

by Qaisar Ali

In Peshawar and adjoining areas (in northern Pakistan), the most popular residential construction is a single- or double-story unreinforced masonry building with 9-inch-thick, solid burnt-brick walls and a 5- to 6-inch reinforced-concrete roof slab. Sometimes, however, 4.5-inch solid brick walls are also used as load-bearing walls. The layout of these dwellings is usually regular, mostly rectangular, having horizontal dimensions in the range of 30 ft x 60 ft or 60 ft x 90 ft, etc. Building height rarely exceeds 35 ft. Wall connections at the corners are achieved through proper toothing. Lintels, approximately 6- to 9-inches deep, with a width equal to the wall thickness, are provided above openings. In a relatively engineered construction, however, the lintel beam runs throughout the perimeter. Similar residential buildings are also found in other cities of Pakistan, for example, in Islamabad and Lahore. In Karachi, Pakistan’s largest city, concrete frame structures with concrete-block infill walls are most often used.

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Filed Under: Asia & Mideast, Masonry, Pakistan, Unreinforced Masonry

Report # 99 : Traditional Nawari house in Kathmandu Valley

August 22, 2011 By

by Dina D’Ayala, Samanta S. R. Bajracharya

The traditional newari house is usually of rectangular plan shape and developed over three storeys. The depth of the plan is usually about six metres with façades of various widths but most commonly between 4 to 8 metres (see also Korn 1976, and NSET-Nepal 2000). The organisation of the house is usually vertical, over 3 storeys, with a spine wall running through the height, creating front and back rooms. At the upper storey the spine wall is sometimes replaced by a timber frame system so as to create a larger continuous space. The staircase is usually a single flight to one side of the plan. The typical interstorey height is quite modest, between 2.20 and 2.50 m., including the floor structure. The bathroom, where present, is found at ground floor, while the kitchen is on the top floor, usually directly under the roof. The first floor is traditionally used as bedrooms, while the second floor is used as living room and for visitors’ reception. There are essentially two types of clusters of houses, either in long arrays, or around a court or chauk . In some cases the two types of clusters are adjacent with some units in common. In the arrays each house has front and back façade free. The construction of each unit is usually independent so that the facades are not continuum over party walls but each unit forms a separate cell. In such cases connection between façades and sidewalls are usually very good. The most interesting characteristic of these buildings both from an architectural and seismic point of view is the presence of the timber frame. Usually at ground floor, on the facade, to provide an open space for workshops or shops. It is also found internally at the upper storeys. In some cases the masonry only forms the outer shell while the internal structure is all made of timber elements. In the better built example of this typology there are a number of construction details, usually made of timber, which, coupled with the brick masonry walls, substantially improve the seismic performance of the overall structure. These features are best preserved in older examples. Currently these buildings are substantially being altered by use of western materials and technology, typically adding concrete frames as upper storeys. This type of intervention highly increases the vulnerability of the existing buildings.

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Filed Under: Asia & Mideast, Masonry, Nepal, Unreinforced Masonry

Report # 91 : Single-storey brick masonry house (EMSB1)

August 22, 2011 By

by Mehedi Ansary

This is a one-story brick masonry house of fired bricks with cement or lime mortar; roof is either GI sheet or another material. These houses can be seen throughout Bangladesh. During the 1918 Srimangal, 1930 Dhubri, and other recent earthquakes, this type of housing suffered heavy damage. Houses with a continuous lintel suffered less.

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Filed Under: Asia & Mideast, Bangladesh, Masonry, Unreinforced Masonry

Report # 86 : Single-family wooden house

August 22, 2011 By

by Norio Maki, Satoshi Tanaka

Japan has a long tradition related to wood construction. The main building of the Horyuji-temple, which was constructed in the late 7th century, is the oldest existing wooden structure in the world. Most Japanese housing is of wood construction. In 1993, 68.1% of the 45.8 million units of housing stock consisted of wooden structures. However, in newly constructed housing, the percentage of wooden structures is decreasing. In 1995, the percentage of wooden structures in newly constructed housing was 45.5%. The Hanshin Awaji earthquake disaster in 1995 damaged many wooden structures, especially housing that was constructed according to the pre-1980 building code. Despite the severe damage at the time of the Hanshin earthquake and governmental encouragement of seismic upgrading, retrofitting of these houses is not common.

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Filed Under: Asia & Mideast, Japan, Timber

Report # 80 : Low-strength dressed stone masonry buildings

August 22, 2011 By

by Ravi Sinha, Vijaya R. Ambati

Construction of stone masonry buildings using easily available local materials is a common practice in both urban and rural parts of India. Stone masonry houses are used by the middle class and lower middle class people in urban areas, and by all classes in rural areas. In rural areas, these buildings are generally smaller in size and are used as single-story, single-family housing. In urban areas, these buildings are up to 4 stories high and are used for multifamily housing. This is a typical load-bearing construction, in which both gravity and lateral loads are resisted by the walls supported by strip footing. If the locally available stone is soft, dressed (shaped) stones are commonly used and can be chiselled at low- or moderate cost. Mud or lime mortar has been used in traditional constructions; however, more recently, cement mortar is being increasingly used. Because soft sandstone is readily available in the Kutch region of Gujarat in the western part of India, stone block masonry constructions are widely used for both single- and multi-story constructions. These houses are usually built by local artisans without formal training and the resulting constructions are structurally weak and incapable of resisting large seismic forces. In the Kutch region, which was affected by the 2001 Bhuj earthquake, this construction type is commonly used with a gable end timber roof truss or RCC roof slabs. Thousands of these houses collapsed in the 2001 Bhuj earthquake resulting in the deaths of large numbers of people. This construction type is inherently unsuitable for areas of moderate-to-high seismic hazard, such as the Kutch region of Gujarat.

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Filed Under: Asia & Mideast, India, Masonry, Stone Masonry, Vernacular
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